The present disclosure relates to the displacement of volume in medical devices such as vascular access devices to provide infusion or other therapy to patients. Infusion therapy is one of the most common health care procedures. Hospitalized, home care, and other patients receive fluids, pharmaceuticals, and blood products via a vascular access device inserted into the vascular system. Infusion therapy may be used to treat an infection, provide anesthesia or analgesia, provide nutritional support, treat cancerous growths, maintain blood pressure and heart rhythm, or many other clinically significant uses.
Infusion therapy is facilitated by vascular access devices located outside the vascular system of a patient (extravascular devices). Extravascular devices that may access a patient's peripheral or central vasculature, either directly or indirectly, include closed access devices, such as the BD Q-SYTE™ closed Luer access device of Becton, Dickinson and Company; syringes; split access devices; catheters; and intravenous (IV) fluid chambers. A vascular access device may be indwelling for short term (days), moderate term (weeks), or long term (months to years). A vascular access device may be used for continuous infusion therapy or for intermittent therapy.
A common vascular access device is a plastic catheter that is inserted into a patient's vein. The catheter length may vary from a few centimeters for peripheral access to many centimeters for central access. The catheter may be inserted transcutaneously or may be surgically implanted beneath the patient's skin. The catheter, or any other extravascular device attached thereto, may have a single lumen or multiple lumens for infusion of many fluids simultaneously.
The proximal end of a vascular access device commonly includes a Luer adapter to which other medical devices may be attached. For example, an administration set may be attached to a vascular access device at one end and an IV bag at the other. The administration set is a fluid conduit for the continuous infusion of fluids and pharmaceuticals. Commonly, an TV access device is a vascular access device that may be attached to another vascular access device, closes or seals the vascular access device, and allows for intermittent infusion or injection of fluids and pharmaceuticals. An IV access device may comprise a housing and a septum for closing the system. The septum may be opened with a blunt cannula or a male Luer of a medical device.
Complications associated with infusion therapy may cause significant morbidity and even mortality. One significant complication is catheter related blood stream infection (CRBSI). An estimate of 250,000-400,000 cases of central venous catheter (CVC) associated BSIs occur annually in US hospitals. Attributable mortality is an estimated 12%-25% for each infection and a cost to the health care system of $25,000-$56,000 per episode.
Vascular access device infection resulting in CRBSIs may be caused by pathogens entering the fluid flow path from refluxed or displaced blood subsequent to catheter insertion. Studies have shown the risk of CRBSI increases with catheter indwelling periods. This may be due, at least in part, to the reflux or displacement of blood from the vascular system of a patient to an extravascular device, such as the catheter. When contaminated, pathogens adhere to the vascular access device, colonize, and form a biofilm. The biofilm is resistant to most biocidal agents and provides a replenishing source for pathogens to enter a patient's bloodstream and cause a BSI.
Certain extravascular devices can operate with each other to form a continuous, extravascular system that provides fluid access to the vascular system, yet is entirely sealed from the external surrounding environment. Such a sealed system limits or supposedly prevents unwanted bacteria from entering from the external surrounding environment through the extravascular devices to the vascular system of a patient.
However, a sealed system of extravascular devices (extravascular system) may function as a closed or sealed vacuum, capable of drawing blood, and consequently a culture for infection, into the extravascular system. As devices are twisted off or otherwise removed from the extravascular system, the volume of the extravascular system is sometimes slightly increased. Because extravascular systems are often less elastic than a patient's vascular system, when the volume of the extravascular system is increased, the volume of a patient's vascular system is decreased under a vacuum pressure from the extravascular system. When the volume of the vascular system decreases, blood flows or is sucked from the vascular system to the extravascular system. Further, as pressure in the extravascular system decreases below the vascular pressure of a patient, either as a result of a change in volume in the extravascular system or another event, blood will flow from the vascular system to the extravascular system.
As recognized in conjunction with the present invention, even a temporary presence of blood within an extravascular system can cause future operational challenges for that extravascular system. For example, blood that clots in the end of a catheter of an extravascular system can block future fluid flow between the extravascular system and a vascular system. If drugs and other fluid substances are forced through the extravascular system causing the blood clot to dislodge from the extravascular system, the blood clot will enter the vascular system causing a dangerous embolism within the patient. Finally, as discussed above, even the rapid entry and exit of blood into the catheter tip of an extravascular system will leave a residue of protein, bacteria, and other pathogens on the inner wall of the catheter. This residue may become a breeding ground for bacteria to grow, and after a given period of time, will cause the formation of a harmful biofilm that is difficult to remove or bypass during extravascular system operation.
Therefore, a need exists for systems and methods that avoid or limit the reflux or displacement of blood from a patient's vascular system into an extravascular system that is connected to the patient's vascular system.